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/* SPDX-License-Identifier: GPL-2.0-only */
/* include/net/xdp.h
* Copyright (c) 2017 Jesper Dangaard Brouer, Red Hat Inc.
#ifndef __LINUX_NET_XDP_H__
#define __LINUX_NET_XDP_H__
#include <linux/skbuff.h> /* skb_shared_info */
* DOC: XDP RX-queue information
* The XDP RX-queue info (xdp_rxq_info) is associated with the driver
* level RX-ring queues. It is information that is specific to how
* the driver have configured a given RX-ring queue.
* Each xdp_buff frame received in the driver carries a (pointer)
* reference to this xdp_rxq_info structure. This provides the XDP
* data-path read-access to RX-info for both kernel and bpf-side
* (limited subset).
* For now, direct access is only safe while running in NAPI/softirq
* context. Contents are read-mostly and must not be updated during
* driver NAPI/softirq poll.
* The driver usage API is a register and unregister API.
* The struct is not directly tied to the XDP prog. A new XDP prog
* can be attached as long as it doesn't change the underlying
* RX-ring. If the RX-ring does change significantly, the NIC driver
* naturally need to stop the RX-ring before purging and reallocating
* memory. In that process the driver MUST call unregister (which
* also applies for driver shutdown and unload). The register API is
* also mandatory during RX-ring setup.
enum xdp_mem_type {
MEM_TYPE_PAGE_SHARED = 0, /* Split-page refcnt based model */
MEM_TYPE_PAGE_ORDER0, /* Orig XDP full page model */
/* XDP flags for ndo_xdp_xmit */
#define XDP_XMIT_FLUSH (1U << 0) /* doorbell signal consumer */
struct xdp_mem_info {
u32 type; /* enum xdp_mem_type, but known size type */
u32 id;
struct page_pool;
struct xdp_rxq_info {
struct net_device *dev;
u32 queue_index;
u32 reg_state;
struct xdp_mem_info mem;
unsigned int napi_id;
} ____cacheline_aligned; /* perf critical, avoid false-sharing */
struct xdp_txq_info {
struct net_device *dev;
struct xdp_buff {
void *data;
void *data_end;
void *data_meta;
void *data_hard_start;
struct xdp_rxq_info *rxq;
struct xdp_txq_info *txq;
u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
static __always_inline void
xdp_init_buff(struct xdp_buff *xdp, u32 frame_sz, struct xdp_rxq_info *rxq)
xdp->frame_sz = frame_sz;
xdp->rxq = rxq;
static __always_inline void
xdp_prepare_buff(struct xdp_buff *xdp, unsigned char *hard_start,
int headroom, int data_len, const bool meta_valid)
unsigned char *data = hard_start + headroom;
xdp->data_hard_start = hard_start;
xdp->data = data;
xdp->data_end = data + data_len;
xdp->data_meta = meta_valid ? data : data + 1;
/* Reserve memory area at end-of data area.
* This macro reserves tailroom in the XDP buffer by limiting the
* XDP/BPF data access to data_hard_end. Notice same area (and size)
* is used for XDP_PASS, when constructing the SKB via build_skb().
#define xdp_data_hard_end(xdp) \
((xdp)->data_hard_start + (xdp)->frame_sz - \
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
static inline struct skb_shared_info *
xdp_get_shared_info_from_buff(struct xdp_buff *xdp)
return (struct skb_shared_info *)xdp_data_hard_end(xdp);
struct xdp_frame {
void *data;
u16 len;
u16 headroom;
u32 metasize:8;
u32 frame_sz:24;
/* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time,
* while mem info is valid on remote CPU.
struct xdp_mem_info mem;
struct net_device *dev_rx; /* used by cpumap */
struct xdp_frame_bulk {
int count;
void *xa;
static __always_inline void xdp_frame_bulk_init(struct xdp_frame_bulk *bq)
/* bq->count will be zero'ed when bq->xa gets updated */
bq->xa = NULL;
static inline struct skb_shared_info *
xdp_get_shared_info_from_frame(struct xdp_frame *frame)
void *data_hard_start = frame->data - frame->headroom - sizeof(*frame);
return (struct skb_shared_info *)(data_hard_start + frame->frame_sz -
SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
struct xdp_cpumap_stats {
unsigned int redirect;
unsigned int pass;
unsigned int drop;
/* Clear kernel pointers in xdp_frame */
static inline void xdp_scrub_frame(struct xdp_frame *frame)
frame->data = NULL;
frame->dev_rx = NULL;
/* Avoids inlining WARN macro in fast-path */
void xdp_warn(const char *msg, const char *func, const int line);
#define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
struct sk_buff *__xdp_build_skb_from_frame(struct xdp_frame *xdpf,
struct sk_buff *skb,
struct net_device *dev);
struct sk_buff *xdp_build_skb_from_frame(struct xdp_frame *xdpf,
struct net_device *dev);
int xdp_alloc_skb_bulk(void **skbs, int n_skb, gfp_t gfp);
struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf);
static inline
void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)
xdp->data_hard_start = frame->data - frame->headroom - sizeof(*frame);
xdp->data = frame->data;
xdp->data_end = frame->data + frame->len;
xdp->data_meta = frame->data - frame->metasize;
xdp->frame_sz = frame->frame_sz;
static inline
int xdp_update_frame_from_buff(struct xdp_buff *xdp,
struct xdp_frame *xdp_frame)
int metasize, headroom;
/* Assure headroom is available for storing info */
headroom = xdp->data - xdp->data_hard_start;
metasize = xdp->data - xdp->data_meta;
metasize = metasize > 0 ? metasize : 0;
if (unlikely((headroom - metasize) < sizeof(*xdp_frame)))
return -ENOSPC;
/* Catch if driver didn't reserve tailroom for skb_shared_info */
if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) {
XDP_WARN("Driver BUG: missing reserved tailroom");
return -ENOSPC;
xdp_frame->data = xdp->data;
xdp_frame->len = xdp->data_end - xdp->data;
xdp_frame->headroom = headroom - sizeof(*xdp_frame);
xdp_frame->metasize = metasize;
xdp_frame->frame_sz = xdp->frame_sz;
return 0;
/* Convert xdp_buff to xdp_frame */
static inline
struct xdp_frame *xdp_convert_buff_to_frame(struct xdp_buff *xdp)
struct xdp_frame *xdp_frame;
if (xdp->rxq->mem.type == MEM_TYPE_XSK_BUFF_POOL)
return xdp_convert_zc_to_xdp_frame(xdp);
/* Store info in top of packet */
xdp_frame = xdp->data_hard_start;
if (unlikely(xdp_update_frame_from_buff(xdp, xdp_frame) < 0))
return NULL;
/* rxq only valid until napi_schedule ends, convert to xdp_mem_info */
xdp_frame->mem = xdp->rxq->mem;
return xdp_frame;
void xdp_return_frame(struct xdp_frame *xdpf);
void xdp_return_frame_rx_napi(struct xdp_frame *xdpf);
void xdp_return_buff(struct xdp_buff *xdp);
void xdp_flush_frame_bulk(struct xdp_frame_bulk *bq);
void xdp_return_frame_bulk(struct xdp_frame *xdpf,
struct xdp_frame_bulk *bq);
/* When sending xdp_frame into the network stack, then there is no
* return point callback, which is needed to release e.g. DMA-mapping
* resources with page_pool. Thus, have explicit function to release
* frame resources.
void __xdp_release_frame(void *data, struct xdp_mem_info *mem);
static inline void xdp_release_frame(struct xdp_frame *xdpf)
struct xdp_mem_info *mem = &xdpf->mem;
/* Curr only page_pool needs this */
if (mem->type == MEM_TYPE_PAGE_POOL)
__xdp_release_frame(xdpf->data, mem);
int xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq,
struct net_device *dev, u32 queue_index, unsigned int napi_id);
void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
void xdp_rxq_info_unused(struct xdp_rxq_info *xdp_rxq);
bool xdp_rxq_info_is_reg(struct xdp_rxq_info *xdp_rxq);
int xdp_rxq_info_reg_mem_model(struct xdp_rxq_info *xdp_rxq,
enum xdp_mem_type type, void *allocator);
void xdp_rxq_info_unreg_mem_model(struct xdp_rxq_info *xdp_rxq);
/* Drivers not supporting XDP metadata can use this helper, which
* rejects any room expansion for metadata as a result.
static __always_inline void
xdp_set_data_meta_invalid(struct xdp_buff *xdp)
xdp->data_meta = xdp->data + 1;
static __always_inline bool
xdp_data_meta_unsupported(const struct xdp_buff *xdp)
return unlikely(xdp->data_meta > xdp->data);
static inline bool xdp_metalen_invalid(unsigned long metalen)
return (metalen & (sizeof(__u32) - 1)) || (metalen > 32);
struct xdp_attachment_info {
struct bpf_prog *prog;
u32 flags;
struct netdev_bpf;
void xdp_attachment_setup(struct xdp_attachment_info *info,
struct netdev_bpf *bpf);
#endif /* __LINUX_NET_XDP_H__ */